Sealing element ventilating means for dry seal gas holders



Feb. 5, 1952 SEALING ELEMENT VENTILATING MEANS FOR DRY SEAL GAS HOLDERSFiled Jan. 24, 1949 FIGB.

INvENToR; JOHN H. w/GG/Ns,

BY ATTORNEY.

Patented Feb. 5, 1952 SEALING ELEMENT VENATIIIIITING MEANS f FOR DRYSEAL GAS HOLDERS John H; Wiggins, Chicago, Ill. Application Januay 24,1949, serial No. 72,505

`4 Claims. (01.48-178) This invention relates to gas holders of thetypethat comprises a flexible, curtain-like fabric element for sealing areciprocating piston that co-acts With a stationary part ,of the casingto form a gas storage chamber of variable volume, and particularly dryseal gas holders of the kind that are equipped with a back-stop againstwhich said sealing element is adapted to be pressed byl the gases in thestorage chamber, during the normal functioning of the apparatus.

In gas holders of the type or kind above mentioned, the curtain-likesealing element is composed of long strips or large pieces of gas-,tightfabric joined together by seams produced. by

f lapping the edge portions of adjacent strips and connecting saidlapped portions to each other by an adhesive. If certain kinds of gasesare stored in such a gas holder, there is a possibility of the pistonsealing element failingor becoming defective as a result of gaspemieating or penetrating the seams of the' piston sealing element` andremaining in contact with the adhesive of a seam ,for a period of timesuicient to soften the adhesive and permit the lapped parts of the seamto separate or pull apart. An'example of a gas which might cause thesealing elementto fail, is benzol vapors stored in a gas holder Whosesealing element is composed of pieces 'of Thiokol rubber joined togetherby an adhesive consist-v ing of neoprene cement, and the reason Why gasthat has penetrated or permeated a seam is liable to soften the adhesiveof the seam, is that the abutment surface of the back-stop bears sotightly against the outer side or air side of the seam, that it trapsthe gas in the seam or connes the gas in the space between the abutmentsurface and the outer side of the seam, with the result that the gasremains in contact with or exerts a deleterious action on the adhesive,for a period of time great enough to soften the adhesive or cause theadhesive to become inactive or inoperative for the purpose for Whichitis employed.

The main object of my invention is to elemi` nate the possibility of theflexible, piston sealing element of a gas holder of the kind above'described failing or becoming defective as a result of gas penetratinga seam of the sealing element and becoming trapped or conned in aposition Where its action on the adhesive of the'seam will cause theadhesive to soften. To thisend I propose to construct the back-stop orabutpenetrated or permeated a seam of the sealing element from'remaining in contact with the cement or other adhesive used to join thelapped portionsnof said seam, the term cement" being herein used tocover any suitable kind of an adhesive for joining `or connectingtogether the piecesof fabric which constitute the piston sealingelement. Brieiiy stated, I'attain' this highly desirable result byconstructing a gas holder of the general type referred to', in such aWay that when the piston sealing element is co-acting With its back-stopor abutment surface, the major portion of the area of said sealingelement will be thoroughly supported yagainst stresses or strains by acontinuous or unbroken surface which stops permeation of gas through thesealing element, and any gas that penetrates or permeates the seams of'the sealing element will not be trappedor conned in a position' wheresaid gas will have a deleterious action on the cement in said seams, butinstead, said gas will be evaporated or carried away from the seams byair which contacts with or rcirculates over the outer sides of theseams. Various means may be used to attain circulation of ai'r'o'rpresence of air between the air side of the sealing element and theback-stop, Without departing from the spirit of my invention. Oneeillcient and inexpensive Way to attain the above described result is toattach raised members to the abutmentV surface of the back-stopinproximity to the seams of the sealing element,` so that When thesealing element is p ressedvagainst the back-stop, said raised memberswill produce air spaces or pas! sagevvays between thezback-stop and theoutside or air'side of the seam portions of the 'sealing element.Another Way'v is to provide they back` stop with air channels'or groovesdisposed so that when the sealing element is in engagement with theback-stop, the outside or air side of the seams of the sealing elementWill be in alignment with said air channels, and the air in saidchannels Will effectively ventilate the seams in the sealing element. Athird Way consists in forming projections or protuberances on theoutside surface of the sealing element adjacent the seams of the sealingelementy so that when the thus expose the outer side or air side of thement surface of an apparatus of the general kind referred to so that ithas the f olloWingcharacteristics or will accomplish the followingresults: A, it will thoroughly support the iiexible piston sealingelement against stresses-ganci strains and insure that approximately %yof said sealing element Will lie against and be backed up by a solidsurface that eifectively stops permeation of gas through said sealingelement;

andB, it will effectively prevent gas that yhas seams in the sealingelement to the action of air.

Figurel ofthe'drawings is a vertical, transverse sectional View of apiston-type, dry-seal gas holder constructed inaccordance with myinvention. Figure 2 is an enlarged, fragmentary, horizontal sectionalview, taken on the line 2 2 of Figure 1. Figure 3 is an enlarged,fragmentary, elevationalvievv, looking radially from the center of thetop side of the piston and showing a portion of the sealing element anda portion of the back-stop on the piston.

Figure 4 is a vertical, longitudinal sectional view, illustratinganother form of my invention, that comprises air channels formed'in thebackstop in longitudinal alignment with the seams of the sealingelement, the back-stop being formed by part of the upper portion of theside wall of the container, and said view being taken on the line 4-4 ofFigure 5.

Figure 5 is a horizontal sectional view of the structure shown in Figure4; and

A Figure 6 is a fragmentary. longitudinal sectional view, illustratingstill another form of my invention, consistinguof protuberances or pro-Jections formed on the outside or air side of the sealingelementadjacent the seams orsaid element. Y

In Figure l of the drawings A and B designate, respectively, the pistonand the stationary container ofthe stationary part of the apparatus thatco-act with each other to form a gasstorage chamber of variable volume.The piston A is sealed by a sealing element C attached to the peripheraledge of the piston and to an intermediate portion of the side wall ofthe container B. The lower portion D of the container side wall isgas-tight and constitutes the side wall of :the gas storage chamber ofthe apparatus, and part of the upper portion of the `container side.wall serves as a back-stop D' for the piston sealing element C duringthe normal functioning of the apparatus. Inasmuch as said back-stop D-is constructed of metal plates, riveted or welded to each other, itforms a continuous, unbroken solid metal surface, which, when engaged bythe sealing element C, thoroughly supports said sealing element againststresses and strains. Also, due vto the fact that said metal surfaceisimpervious or non-porous, it effectively stops permeation of gas through.the fabric of which the piston sealing element C is constructed. In thegas holder herein illustrated the piston is also provided with aback-stop for thesealing element, formed by an annular member E thatprojects upwardly from the top side of the piston at the peripheral edgeof the piston, said member E also being preferably constructed of metalplates so as to produce a supporting surface having the samecharacteristics as the backstop D'. When the piston A is-in-itslowermost position, as shown in broken lines in Figure l, the gases inthe storage chamber of the apparatus exert pressure on the sealingelement C ina direction to press a portion of said sealing element intosnug engagement with the backstop E on the piston, and when the pistonmoves upwardly,l as shown in solid lines in Figure l-, the sealingelement C is stripped off the backstop E on the piston and applied tothe backstop D on the container side wall. Asis usual in gas holdersequipped with a flexible, curtainlike "dry-seal C, said seal is composedof long strips or large pieces of gas-tight fabric whose adjacent edgeportions are lapped and joined together by cement or any suitable kindof an adhesive, so as to produce cemented seams zr. as shown in Figure2.`

As previously explained, if gas penetrates or I permeates through a seamofthe fabric sealing element C, there is danger of said sealing elementfailing, if such gas is allowed to remain in contact with or in closeproximity to the cement of the seam. long enough to cause the cement tosoften and permit the lapped parts of the seam to separate or pullapart. In order to eliminate the possibility of this happening, Iconstruct the apparatus in such a way that when the sealing element C isin engagement with either one or both of the back-stops D' or E. theseams n: in the portion or portions of the sealing elementcontacted bysaid back-stop or back-stops, will be effectively ventilated on the airside of said seams, with the result that any gas that has penetrated orpermeated said seams will escape to the atmosphere, and accordingly,prevented from softening or having a deleterious action on the cement ofthe seams.

In the form of my invention shown in Figures l, 2 and 3,vertically-disposed members, usually consisting of straight rods orstrips l, are attached to the outer side of the back-stop E on thepiston in vertical alignment with the seams :c of the sealing element C,so that when a portion -of said sealing element is pressed against theback-stop E, as shown in Figure 2, air circulating channels orpassageways y will be formed between the back-stop E and the outside orair side of the seams a' in the portion of thesealing element contactedby the back-stop E. Similar vertically disposed strips or rods la arealso attached to the inner face of the portion of the tank side wallthat constitutes the back-stop D', so that when a portion of the sealingelement is in engagement with the back-stop D', the strips orlongitudinally-disposed projections IEL on the back-stop D' will preventthe outer sides of the seams :z: in the said portion of the sealingelement from snugly engaging or bearing against said back-stop D.Obviously, the above mentioned strips I and In should be made of suchdimensionin .cross section that the portions of the piston sealingelement between the seams :c will snugly engage the solid supportingsurfaces of the back-stops. It will thus be seen that back-stops of thekind above described, in addition to forming solid or continuoussupporting surfaces that back up the entire area of the portions of thepiston sealing element engaged by same, also effectively ventilate theseams in portions of the sealing element C contacted by the back-stops,and prevent gas that has penetrated or seeped through such seams frombeing trapped or confined in a position where it is liable to soften thecement of the seams and cause the seams to fail. In order to insure anadequate supply of air to the air circulating channels or passageways y,I form small air holes or Ventilating ports e in the back-stop Epreferably at intervals throughout the height of the strips I on saidback-stop and in close proximity to said strips, and I also form similarsmall air ports z in the back-stop D', preferably at the lower end ofthe strips l, as shown in Figure l.

Instead of providing the back-stops of the apparatus with strips orequivalent raised devices l and I'L disposed in alignment with the seamsof the sealing element C in such a way as to ventilate or aerate the airside of said seams during the time the back-stops are operating toabsorb pressure exerted by the stored gases on the sealing element C, Ican form air channels orcirculating passageways in the back-stops inlongitudinal alignment with the seams a: of the sealing element C, asshown in Figures 4 and 5.' Said figures illustrate air channels orcirculating passageways 2 formed in the side wall back-stop D byoutwardly-projecting, channel-shaped portions 2a on the said back-stop.

In such a structure the outer side or air side of the seams :r in thesealing element C that are disposed in longitudinal alignment with theair circulating passageways 2 will be eiectively Ventilated by the airchannels 2 in the way and for the purpose described. When a means of thekind shown in Figures 4 and 5 is used for ventilating the seams in theportion of the sealing element contacted by the back-stop E on thepiston, said back-stop E is provided with channel-shaped portions 2athat project inwardly towards the center of the piston, thus forming airchannels in the surface of the back-stop that is presented to the airside of the sealing element C.

In Figure 6 of the drawings I have illustrated still another inexpensiveand efilcient means for Ventilating or supplying air to the air side ofthe seams of the sealing element C, consisting of protuberances 3attached to the outer side or air side of the sealing element C alongthe length of the seams a: in said sealing element, and smallVentilating openings or air ports 3B formed in the back-stop at suchpoints that when said protuberances 3 are in engagement with theback-stop, air will contact with or circulate over the air side of theseams in the piston sealing element, and the portions of said sealingelement located between said seams will lie snugly against and bethoroughly supported by said imperforate portions of the backstops.

The drawings illustrate the sealing element C as being composed oflongitudinally-disposed strips of fabric joined together by seams x thatextend vertically of the back-stops when the sealing element is inengagement with the backstops. In the event the sealing elementcomprises seams that are disposed transversely of the sealing elementand which extend horizontally of the back-stops when the sealing elementis in engagement with the back-stops, such horizontally-disposed seamswould be ventilated or supplied with air by means or devices `of thekind previously described, arranged so as to permit or cause air tocirculate between the backstop and the air side of the seams in theportions of the sealing element contacted by the backstops.

In the claims I have used the rather cumbersome expression seams in theportion of the sealing element contacted by the back-stop to make itclear that my invention contemplates Ventilating the seams in thesealing element, only when said seams are arranged in such relationshipwith a back-stop, that the back-stop might trap or confine gas that haspenetrated a seam and come in contact with the adhesive used to join thetwo lapped portions of the same. In any type or kind of gas holderprovided with a seal formed by a curtain-like fabric element andequipped with a back-stop for said sealing element, there are periods inthe cycle of operations of the apparatus, when portions of the sealingelement do not press against the back-stop. For example, during theupward movement of the piston, the piston sealing element assumes theform of an upwardly-disposed loop, as shown in Figure 1, but there is notendency for gas to concentrate in seams in the portion of the sealingelement that is disposed in the form of a loop, due to the fact that theoutside face or air side of said looped portion is presented to the air,and hence, any gas that might penetrate a seam of said looped portion,will evaporate or escape into the air instead of remaining in engagement6 with the adhesive used in said seam. It is for this reason that I haveused the expression previously quoted.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A gas holder provided with a reciprocating piston and a stationarypart that co-act with each other to form a gas storage chamber ofvariable volume, a sealing element for said piston formed from aplurality of pieces of gas-tight fabric joined together by cementedseams, a back-stop against which said sealing element is adapted to bepressed by the gases in the storage chamber, said back-stop having asolid surface that backs up the pieces of fabric located between theseams of said sealing element and stops permeation of gas through saidfabric, and

devices located on the air side of said sealing element in longitudinalalignment with the seams in said element and disposed so as to hold atleast a portion of the outside faces of said seams, out of contact withthe back stop, whereby air can circulate over the outer side of saidseams and carry away gas that has permeated or penetrated into saidseams from the storage chamber.

2. A gas holder of the kind described in claim l, in which the devicesthat hold at least a portion of the outside faces of the seams of thesealing element out of contact with the backstop, consist of stripsmounted stationarily on the back stop and projecting forwardly from thesurface of same contacted by the sealing element, so as to lie betweenthe back stop and the sealing element in the zones of the seams of thesealing element when said sealing element is pressed against the backstop.

3. A gas holder of the kind described in claim 1, in which the devicesthat hold at least a portion of the outside faces of the seams of thesealing element out of contact with the backstop, consist ofprotuberances on the air side of the sealing element, located at oneside of each seam of said element and arranged in spaced relation alongthe length of the seams, said protuberances projecting beyond said seamsso as to bear against the back stops and hold said seams spaced awayfrom the back stop.

4. A gas holder of the kind described in claim 1, in which the devicesthat hold at least a portion of the outside faces of the seams of thesealing element out of contact with the back stop, consist of grooves inthe surface of the back stop contacted by the sealing element. disposedso that when the sealing element is pressedagainst the back stop, theseams in said element lie in direct longitudinal alignment with saidgrooves and with the outside faces of said seams spaced away from thebottoms of said grooves.

JOHN H. WIGGINS.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,050,685 Wiggins Aug. 11, 19362,194,581 Weichsel Mar. 26, 1940 2,478,731 Wiggins Aug. 9, 1949 FOREIGNPATENTS Number Country Date 4,790 Great Britain of 1823

